Hurricane season may shift into neutral, Colorado State forecasters say

Atlantic coastal areas will be looking at below average tropical activity at least through the middle of August, Colorado State University hurricane experts William Gray and Philip Klotzbach said in a report Friday.

Whatever storms do manage to form will probably be weak, they said. They were basing their forecast around the Accumulated Cyclone Energy (ACE) index, defined as all of a storm’s maximum wind speeds for each six-hours of existence over a two-week period. The average for Aug. 2 to Aug. 15 is 7 units; Klotzbach and Gray expect 4 or fewer units to be generated.

At the same time, the pair released their final 2013 seasonal forecast and maintained their projected 18 named storms. But they dropped the number of forecast hurricanes from nine to eight, and major hurricanes, Category 3 and higher, from four to three.

They said there was a 64 percent chance of an East Coast hit by a major hurricane, compared with a 100-year average of 52 percent. And they said the Florida peninsula and Gulf Coast were still at higher risk from a major hurricane than average.

Specifically, they said Florida had a 63 percent chance of experiencing a landfalling hurricane, compared with an average 11 percent, and a 28 percent chance of getting hit with a major hurricane, up from 21 percent.

The peak of the season however, may have a late start.

The number of named storms usually begins to ramp up dramatically in early August, but this year something called the Madden-Julian Oscillation, a pattern of increased thunderstorm activity that travels around the world in tropical zones, is expected to be weak over the Atlantic. That’s one reason why computer forecast models are showing nothing tropical popping up over at least the next 10 days.

The researchers have been forecasting an above average season and aren’t backing away from that — at least for now. They expect to publish additional two-week forecasts on Aug. 16, Aug. 30, Sept. 13, Sept. 27 and Oct. 11.

* * *

EX-DORIAN: The remnants of Tropical Storm Dorian showed signs of life Thursday and Friday as it moved through the Bahamas. The National Hurricane Center began new model runs on the area of showers and storms, re-naming it Invest 91L, and placed chances of regeneration at between 30-40 percent.

The system pushed as far west as the waters between the Bahamas and the South Florida peninsula, but it appears it will have only minor impact on land as the low drifts north off the coast.

At first, very early Friday morning, National Weather Service forecasters said heavy rain was possible with 3 inches on the East Coast. But by 7:30 a.m., the low was about 60 miles east of South Florida and was moving north. Some afternoon showers were still possible, forecasters said. They put rain chances at 70 percent, dropping to 50 percent Friday night and 30 percent Saturday.